Cormorant Global Healthcare Master Fund Form 4 PROTEOSTASIS THERAPEUTICS / Bihua Chen ownership change

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person^*

Cormorant Asset Management, LLC

(Last) (First) (Middle)

200 CLARENDON STREET, 52ND FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
PROTEOSTASIS THERAPEUTICS, INC. [ PTI ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

Director	X	10% Owner
Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
12/07/2016

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

	Form filed by One Reporting Person
X	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	12/07/2016		P		22,598	A	$10.7402(3)	3,660,907	I	See Footnotes(1)(2)(3)
Common Stock	12/08/2016		P		21,819	A	$10.93(4)	3,682,726	I	See Footnotes(1)(2)(4)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person^*

Cormorant Asset Management, LLC

(Last) (First) (Middle)

200 CLARENDON STREET, 52ND FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

1. Name and Address of Reporting Person^*

Chen Bihua

(Last) (First) (Middle)

C/O CORMORANT ASSET MANAGEMENT, LLC

200 CLARENDON STREET, 52ND FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

1. Name and Address of Reporting Person^*

Cormorant Global Healthcare GP, LLC

(Last) (First) (Middle)

200 CLARENDON STREET, 52ND FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

1. Name and Address of Reporting Person^*

Cormorant Global Healthcare Master Fund, LP

(Last) (First) (Middle)

200 CLARENDON STREET, 52ND FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

Explanation of Responses:

1. Shares reported herein are held by Cormorant Global Healthcare Master Fund, LP (the "Master Fund") and by a managed account (the "Account"). Cormorant Asset Management, LLC ("Cormorant") serves as the investment manager of the Master Fund and the Account. Cormorant Global Healthcare GP, LLC ("GP LLC") serves as General Partner of the Master Fund. Bihua Chen serves as manager of Cormorant and GP LLC. GP LLC may be deemed to beneficially own the shares held by the Master Fund, and Cormorant and Ms. Chen may be deemed to beneficially own the shares held by the Master Fund and the Account.

2. Each of the Reporting Persons disclaims beneficial ownership of the shares reported herein except to the extent of its or her pecuniary interest therein, and the filing of this Form 4 shall not be construed as an admission that any of the Reporting Persons is the beneficial owner of any such shares for purposes of Section 16(a) of the Securities Exchange Act of 1934 or for any other purpose.

3. Represents the weighted average purchase price of shares purchased in a series of open market transactions on the transaction date at prices ranging from $10.50 to $10.75 per share. The Reporting Persons undertake to provide, upon request by the staff of the Securities and Exchange Commission, the issuer, or a security holder of the issuer, full information regarding the number of shares purchased at each price. Of these shares, 18,790 were purchased for the Master Fund and 3,808 shares were purchased for the Account. As of December 7, 2016, the Master Fund held 3,044,422 shares, and the Account held 616,485 shares.

4. Represents the weighted average purchase price of shares purchased in a series of open market transactions on the transaction date at prices ranging from $10.67 to $11.00 per share. The Reporting Persons undertake to provide, upon request by the staff of the Securities and Exchange Commission, the issuer, or a security holder of the issuer, full information regarding the number of shares purchased at each price. Of these shares, 18,142 were purchased for the Master Fund and 3,677 shares were purchased for the Account. As of December 8, 2016, the Master Fund held 3,062,564 shares, and the Account held 620,162 shares.

	/s/ CORMORANT GLOBAL HEALTHCARE GP, LLC By: Bihua Chen, Managing Member	12/09/2016
	/s/ CORMORANT ASSET MANAGEMENT, LLC By: Bihua Chen, Managing Member	12/09/2016
	/s/ CORMORANT GLOBAL HEALTHCARE MASTER FUND, LP By: Cormorant Global Healthcare GP, LLC, its General Partner By: Bihua Chen, Managing Member	12/09/2016
	/s/ Bihua Chen	12/09/2016
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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